This invention relates to an improvement of the tamper-evident form disclosed in International Patent Application PCT/AU98/00787 filed Sep. 18, 1998 claiming priority from Australian Provisional Patent Application PP0273 filed Nov. 7, 1997.
The disclosure of International Patent Application PCT/AU98/00787 is hereby incorporated by cross-reference and a complete understanding of the present invention requires reference to the above document.
International Patent Application PCT/AU98/00787 discloses a tamper-evident form for securely carrying information. Confidential information can be printed on the form with a non-impact printer (eg. laser printer or ink jet printer) and the form does not require further processing (eg. folding or coating etc) after printing in order to render the confidential information printed on the form secure. As such, it represents a significant advance over the previous known art in the field of secure forms.
A number of the preferred embodiments disclosed in PCT/AU98/00787 involve a multi-ply construction involving a transparent laminate and an underlying substrate which bears a scrambling pattern which is visible through the transparent laminate such that information printed on the transparent laminate cannot be read or ascertained until the transparent laminate and underlying scrambling pattern are physically separated.
In some embodiments an incomplete die cut (which leaves frangible ties) is provided in either the substrate or the transparent laminate and a portion of the substrate or a portion of the laminate is removable from the remainder of the substrate or laminate, respectively, to thereby render the confidential information on the transparent laminate visible.
These embodiments rely on frangible ties in the substrate or laminate, respectively, to indicate tampering. A concern with these embodiments is the fact that detection of tampering is reliant on the user observing the fact that the frangible ties are broken. A further concern is that the entire laminate could be lifted away from the substrate without breaking the frangible ties and thereafter the entire laminate could be carefully replaced on the substrate with there being no evidence of tampering at all.
According to a first aspect, the invention resides in a tamper-evident form including:
a transparent upper laminate having a textured lower surface and adapted to receive confidential information on its upper surface;
a lower laminate having a complementary textured upper surface such that the upper laminate appears transparent and such that the upper laminate appears noticeably less transparent when it is separated from the lower laminate and the complementary textured surfaces are exposed.
According to a second aspect, the invention resides in a tamper-evident form including:
a transparent upper laminate adapted to receive confidential information; and
a lower laminate, wherein the upper surface of the lower laminate and the lower surface of the upper laminate are complementary in shape such that separation of the upper and lower laminates exposes that complementary surfaces and decreases the transparency of at least the upper laminate.
According to a third aspect the invention resides in a tamper-evident form including:
an upper laminate bonded to a lower laminate, the arrangement being such that, when bonded, the combined laminates are transparent and, when separated, the separated laminates are noticeably less transparent.
According to a fourth aspect the invention resides in a method of indicating separation of a first transparent laminate and a second laminate, wherein the first transparent laminate is adapted to receive confidential information and wherein the second laminate includes an associated scrambling pattern which prevents reading of the confidential information, the method including:
forming complementary textured surfaces at the juncture of the first and second laminates, whereby separation of the laminates exposes the complementary textured surfaces and alters the optical properties of at least the first transparent laminate.